Diamond-Blackfan anemia: genotype-phenotype correlations in Italian patients with RPL5 and RPL11 mutations

Background Diamond-Blackfan anemia is a rare, pure red blood cell aplasia of childhood due to an intrinsic defect in erythropoietic progenitors. About 40% of patients display various malformations. Anemia is corrected by steroid treatment in more than 50% of cases; non-responders need chronic transfusions or stem cell transplantation. Defects in the RPS19 gene, encoding the ribosomal protein S19, are the main known cause of Diamond-Blackfan anemia and account for more than 25% of cases. Mutations in RPS24 , RPS17 , and RPL35A described in a minority of patients show that Diamond-Blackfan anemia is a disorder of ribosome biogenesis. Two new genes ( RPL5 , RPL11 ), encoding for ribosomal proteins of the large subunit, have been reported to be involved in a considerable percentage of patients. Design and Methods In this genotype-phenotype analysis we screened the coding sequence and intron-exon boundaries of RPS14 , RPS16 , RPS24 , RPL5 , RPL11 , and RPL35A in 92 Italian patients with Diamond-Blackfan anemia who were negative for RPS19 mutations. Results About 20% of the patients screened had mutations in RPL5 or RPL11 , and only 1.6% in RPS24 . All but three mutations that we report here are new mutations. No mutations were found in RPS14 , RPS16 , or RPL35A . Remarkably, we observed a higher percentage of somatic malformations in patients with RPL5 and RPL11 mutations. A close association was evident between RPL5 mutations and craniofacial malformations, and between hand malformations and RPL11 mutations. Conclusions Mutations in four ribosomal proteins account for around 50% of all cases of Diamond-Blackfan anemia in Italian patients. Genotype-phenotype data suggest that mutation screening should begin with RPL5 and RPL11 in patients with Diamond-Blackfan anemia with malformations.